Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1761997Ab3EBT4y (ORCPT ); Thu, 2 May 2013 15:56:54 -0400 Received: from mga11.intel.com ([192.55.52.93]:30300 "EHLO mga11.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1761345Ab3EBT4x (ORCPT ); Thu, 2 May 2013 15:56:53 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.87,597,1363158000"; d="scan'208";a="331473246" Message-ID: <1367524609.19739.8.camel@ideak-mobl> Subject: Re: [PATCH] wait: fix false timeouts when using wait_event_timeout() From: Imre Deak To: Jens Axboe Cc: David Howells , Daniel Vetter , "Paul E. McKenney" , Dave Jones , Lukas Czerner , linux-kernel@vger.kernel.org Date: Thu, 02 May 2013 22:56:49 +0300 In-Reply-To: <20130502123517.GL7800@kernel.dk> References: <1367485129-4423-1-git-send-email-imre.deak@intel.com> <3633.1367497784@warthog.procyon.org.uk> <20130502123517.GL7800@kernel.dk> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.6.2-0ubuntu0.1 Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1555 Lines: 38 On Thu, 2013-05-02 at 14:35 +0200, Jens Axboe wrote: > On Thu, May 02 2013, David Howells wrote: > > Imre Deak wrote: > > > > > Many callers of the wait_event_timeout() and > > > wait_event_interruptible_timeout() expect that the return value will be > > > positive if the specified condition becomes true before the timeout > > > elapses. However, at the moment this isn't guaranteed. If the wake-up > > > handler is delayed enough, the time remaining until timeout will be > > > calculated as 0 - and passed back as a return value - even if the > > > condition became true before the timeout has passed. > > > > > > Fix this by returning at least 1 if the condition becomes true. This > > > semantic is in line with what wait_for_condition_timeout() does; see > > > commit bb10ed09 - "sched: fix wait_for_completion_timeout() spurious > > > failure under heavy load". > > > > > > Signed-off-by: Imre Deak > > > > Acked-by: David Howells > > You can add mine, too: > > Acked-by: Jens Axboe Ok, I think we agree that the +1 thing in schedule_timeout() discussed in this thread should be handled separately, so if there is no other objection I'd be happy if this patch was merged through someone's tree as-is. --Imre -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/